JP6197610B2 - Positive electrode active material, positive electrode and lithium ion secondary battery - Google Patents

Positive electrode active material, positive electrode and lithium ion secondary battery Download PDF

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JP6197610B2
JP6197610B2 JP2013247301A JP2013247301A JP6197610B2 JP 6197610 B2 JP6197610 B2 JP 6197610B2 JP 2013247301 A JP2013247301 A JP 2013247301A JP 2013247301 A JP2013247301 A JP 2013247301A JP 6197610 B2 JP6197610 B2 JP 6197610B2
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友彦 加藤
友彦 加藤
佐野 篤史
篤史 佐野
秀明 関
秀明 関
中野 博文
博文 中野
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Description

本発明は、正極活物質、正極及びリチウムイオン二次電池に関する。   The present invention relates to a positive electrode active material, a positive electrode, and a lithium ion secondary battery.

従来、リチウムイオン二次電池の正極材料(正極活物質)としてLiCoOやLiNi1/3Mn1/3Co1/3等の層状化合物やLiMn等のスピネル化合物が用いられてきた。近年では、LiFePOに代表されるオリビン型構造の化合物が注目されている。オリビン構造を有する正極材料は高温での熱安定性が高く、安全性が高いことが知られている。しかし、LiFePOを用いたリチウムイオン二次電池は、その充放電電圧が3.5V程度と低く、エネルギー密度が低くなるという欠点を有する。そのため、高い充放電電圧を実現し得るリン酸系正極材料として、LiCoPOやLiNiPO等が提案されている。しかし、これらの正極材料を用いたリチウムイオン二次電池においても、十分な容量が得られていないのが現状である。 Conventionally, a layered compound such as LiCoO 2 or LiNi 1/3 Mn 1/3 Co 1/3 O 2 or a spinel compound such as LiMn 2 O 4 has been used as a positive electrode material (positive electrode active material) of a lithium ion secondary battery. It was. In recent years, compounds having an olivine type structure typified by LiFePO 4 have attracted attention. It is known that a positive electrode material having an olivine structure has high thermal stability at high temperatures and high safety. However, the lithium ion secondary battery using LiFePO 4 has a drawback that its charge / discharge voltage is as low as about 3.5 V and the energy density is low. Therefore, LiCoPO 4 , LiNiPO 4, and the like have been proposed as phosphoric acid-based positive electrode materials that can realize a high charge / discharge voltage. However, the present situation is that a sufficient capacity is not obtained even in lithium ion secondary batteries using these positive electrode materials.

そのため、高い充放電電圧を実現し、かつ十分な容量が得られるリン酸系正極材料として、LiVOPOが提案されている(特許文献1)。 Therefore, LiVOPO 4 has been proposed as a phosphoric acid-based positive electrode material that realizes a high charge / discharge voltage and provides a sufficient capacity (Patent Document 1).

しかしながら、特許文献1記載された方法により得られたLiVOPOを用いた正極を備える電池では、十分なサイクル特性を得られるものではなかった。 However, in a battery provided with a positive electrode using LiVOPO 4 obtained by the method described in Patent Document 1, sufficient cycle characteristics cannot be obtained.

特開2004−303527号公報JP 2004-303527 A

本発明は、上記従来技術の有する課題に鑑みてなされたものであり、十分な容量が得られ、かつ良好なサイクル特性が得られる正極活物質、正極及びリチウムイオン二次電池を提供することを目的とする。   The present invention has been made in view of the above-described problems of the prior art, and provides a positive electrode active material, a positive electrode, and a lithium ion secondary battery that can provide sufficient capacity and good cycle characteristics. Objective.

上記目的を達成するために本発明に係る正極活物質は、三斜晶の結晶構造を有するLiVOPOの(200)面の回折ピークの半値幅が0.114°以上0.175°以下であり、かつ、平均一次粒子径が0.07μm以上0.6μm以下であることを特徴とする。 In order to achieve the above object, the positive electrode active material according to the present invention has a half-width of the diffraction peak of the (200) plane of LiVOPO 4 having a triclinic crystal structure of 0.114 ° to 0.175 °. And an average primary particle diameter is 0.07 micrometer or more and 0.6 micrometer or less, It is characterized by the above-mentioned.

本発明によれば、従来と比較して十分な容量及び従来と比較して良好なサイクル特性を実現することができる。この理由としては必ずしも明らかではないが、次のように考えられる。   According to the present invention, it is possible to realize sufficient capacity as compared with the conventional case and good cycle characteristics as compared with the conventional case. Although the reason for this is not necessarily clear, it can be considered as follows.

三斜晶の結晶構造を有するLiVOPOの回折パターンの2θ=29.6°付近における(200)面の回折ピークの半値幅は、正極活物質の結晶性や結晶子サイズを反映し、半値幅が小さいほど結晶性は高く結晶子サイズは大きく、半値幅が大きいほど結晶性は低く結晶子サイズは小さくなる関係にある。そこで、(200)面の回折ピークの半値幅が0.114°以上の場合、高容量が得られる程度の小さい結晶子サイズになりやすく、半値幅が0.175°以下の場合、充電放電の繰り返しによるLiの挿入脱離に対して安定である程度に結晶性が高いため、良好なサイクル特性が実現できると考えられる。さらに、平均一次粒子径が0.07μmより以上であると、比表面積が比較的小さいため、正極活物質表面と電解液との反応の影響が小さく、良好なサイクル特性が得られる傾向となり、0.6μm以下であると正極活物質中のリチウムイオンの拡散距離が短くなるため、十分な容量が得られる傾向となる。 The full width at half maximum of the diffraction peak of the (200) plane in the vicinity of 2θ = 29.6 ° of the diffraction pattern of LiVOPO 4 having a triclinic crystal structure reflects the crystallinity and crystallite size of the positive electrode active material. The smaller the value, the higher the crystallinity and the larger the crystallite size, and the larger the half width, the lower the crystallinity and the smaller the crystallite size. Therefore, when the half-value width of the diffraction peak on the (200) plane is 0.114 ° or more, the crystallite size tends to be small enough to obtain a high capacity, and when the half-value width is 0.175 ° or less, charge discharge It is considered that good cycle characteristics can be realized because the crystallinity is stable to a certain extent and stable against repeated Li insertion and desorption. Further, when the average primary particle diameter is 0.07 μm or more, the specific surface area is relatively small, so that the influence of the reaction between the surface of the positive electrode active material and the electrolytic solution is small, and good cycle characteristics tend to be obtained. When the thickness is 0.6 μm or less, the diffusion distance of lithium ions in the positive electrode active material is shortened, so that a sufficient capacity tends to be obtained.

以上のことより、(200)面の回折ピークの半値幅が0.114°以上0.175°以下であり、かつ、平均一次粒子径が0.07μm以上0.6μm以下である場合、十分な容量が得られ、かつ良好なサイクル特性を合わせ持つことが可能となると考えられると考えられる。   From the above, it is sufficient when the half width of the diffraction peak of (200) plane is 0.114 ° or more and 0.175 ° or less and the average primary particle size is 0.07 μm or more and 0.6 μm or less. It is considered that it is possible to obtain a capacity and to have a good cycle characteristic.

また、三斜晶の結晶構造を有するLiVOPOの(002)面の回折ピークの半値幅が0.118°以上0.185°以下であることが好ましい。これにより、良好なサイクル特性を実現できる。2θ=22.4°付近における(002)面の回折ピークの半値幅が0.118°以上の場合、高容量が得られる程度の小さい結晶子サイズになりやすく、半値幅が0.185°以下の時には、正極活物質の結晶性がより高く、繰り返し充電放電を行った場合にも、十分な容量が得られ、かつより良好なサイクル特性が実現できると考えられる。 Moreover, it is preferable that the half width of the diffraction peak of the (002) plane of LiVOPO 4 having a triclinic crystal structure is 0.118 ° or more and 0.185 ° or less. Thereby, a favorable cycle characteristic is realizable. When the half width of the diffraction peak of the (002) plane near 2θ = 22.4 ° is 0.118 ° or more, the crystallite size tends to be small enough to obtain a high capacity, and the half width is 0.185 ° or less. In this case, it is considered that the crystallinity of the positive electrode active material is higher and sufficient capacity can be obtained and better cycle characteristics can be realized even when repeated charge and discharge are performed.

発明者らは、鋭意検討を重ねた結果、三斜晶の結晶構造を有するLiVOPOの(200)面および(002)面の回折ピークの半値幅と、容量およびサイクル特性とに密接な相関関係があることを見出した。この理由としては(200)面および(002)面において、特に焼成工程、粉砕工程および分級工程などで結晶性への影響を受けやすい傾向があるものと考えられる。 As a result of intensive studies, the inventors have found that there is a close correlation between the half-value widths of the diffraction peaks of the (200) plane and (002) plane of LiVOPO 4 having a triclinic crystal structure, and the capacity and cycle characteristics. Found that there is. The reason for this is considered that the (200) plane and the (002) plane tend to be easily affected by the crystallinity particularly in the firing step, pulverization step, classification step and the like.

また、本発明に係る正極は、集電体と上記正極活物質を含み、前記集電体上に設けられた正極活物質層と、を備えることにより、十分な容量が得られ、かつ良好なサイクル特性を得ることができる。   In addition, the positive electrode according to the present invention includes a current collector and the positive electrode active material, and includes a positive electrode active material layer provided on the current collector, whereby a sufficient capacity can be obtained and good. Cycle characteristics can be obtained.

また、本発明に係るリチウムイオン二次電池は、上記正極を備えることにより、十分な容量が得られ、かつ良好なサイクル特性を得ることができる。   Moreover, the lithium ion secondary battery which concerns on this invention can provide sufficient capacity | capacitance by providing the said positive electrode, and can acquire favorable cycling characteristics.

本発明によれば、良好なサイクル特性が得られる正極活物質、正極及びリチウムイオン二次電池を提供することができる。   According to the present invention, it is possible to provide a positive electrode active material, a positive electrode, and a lithium ion secondary battery that can obtain good cycle characteristics.

本実施形態に係るリチウムイオン二次電池の模式断面図である。It is a schematic cross section of the lithium ion secondary battery according to the present embodiment.

以下、図面を参照しながら本発明の好適な実施形態について説明する。なお、本発明は以下の実施形態に限定されるものではない。また以下に記載した構成要素には、当業者が容易に想定できるもの、実質的に同一のものが含まれる。さらに以下に記載した構成要素は、適宜組み合わせることができる。   Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

<リチウムイオン二次電池>
本実施形態に係るリチウムイオン二次電池について図1を参照して簡単に説明する。
<Lithium ion secondary battery>
The lithium ion secondary battery according to this embodiment will be briefly described with reference to FIG.

リチウムイオン二次電池100は、主として、積層体30、積層体30を密閉した状態で収容するケース50、及び積層体30に接続された一対のリード60,62を備えている。   The lithium ion secondary battery 100 mainly includes a laminate 30, a case 50 that accommodates the laminate 30 in a sealed state, and a pair of leads 60 and 62 connected to the laminate 30.

積層体30は、正極10及び負極20がセパレータ18を挟んで対向配置されたものである。正極10は、正極集電体12上に正極活物質層14が設けられた物である。負極20は、負極集電体22上に負極活物質層24が設けられた物である。正極活物質層14及び負極活物質層24がセパレータ18の両側にそれぞれ接触している。正極集電体12及び負極集電体22の端部には、それぞれリード60,62が接続されており、リード60,62の端部はケース50の外部にまで延びている。
<正極活物質>
続いて、本実施形態に係る正極活物質について説明する。
The laminated body 30 is configured such that the positive electrode 10 and the negative electrode 20 are disposed to face each other with the separator 18 interposed therebetween. The positive electrode 10 is a product in which a positive electrode active material layer 14 is provided on a positive electrode current collector 12. The negative electrode 20 is a product in which a negative electrode active material layer 24 is provided on a negative electrode current collector 22. The positive electrode active material layer 14 and the negative electrode active material layer 24 are in contact with both sides of the separator 18. Leads 60 and 62 are connected to the end portions of the positive electrode current collector 12 and the negative electrode current collector 22, respectively, and the end portions of the leads 60 and 62 extend to the outside of the case 50.
<Positive electrode active material>
Then, the positive electrode active material which concerns on this embodiment is demonstrated.

本実施形態に係る正極活物質は、三斜晶の結晶構造を有するLiVOPOの(200)面の回折ピークの半値幅が0.114°以上0.175°以下であり、かつ、平均一次粒子径が0.07μm以上0.6μm以下である。さらに、(002)面の回折ピークの半値幅が0.118°以上0.185°以下であることがより好ましい。 In the positive electrode active material according to this embodiment, the half-value width of the diffraction peak of the (200) plane of LiVOPO 4 having a triclinic crystal structure is 0.114 ° or more and 0.175 ° or less, and average primary particles The diameter is 0.07 μm or more and 0.6 μm or less. Furthermore, it is more preferable that the half width of the diffraction peak on the (002) plane is 0.118 ° or more and 0.185 ° or less.

回折ピークの半値幅は正極活物質の結晶性や結晶子サイズを反映し、半値幅が小さいほど結晶性は高く結晶子サイズは大きく、半値幅が大きいほど結晶性は低く結晶子サイズは小さくなる関係にあり、十分な容量が得られる結晶子サイズと、充電放電の繰り返しに対して安定である程度に高い結晶性を持つ正極活物質を用いることにより、十分な容量が得られ、かつ良好なサイクル特性が実現できると考えられる。   The half width of the diffraction peak reflects the crystallinity and crystallite size of the positive electrode active material. The smaller the half width, the higher the crystallinity and the larger the crystallite size, and the larger the half width, the lower the crystallinity and the smaller the crystallite size. There is a relationship between the crystallite size that provides a sufficient capacity, and a positive electrode active material that is stable against repeated charging and discharging and has a high degree of crystallinity. It is considered that the characteristics can be realized.

正極活物質の半値幅の算出方法は粉末X線回折法により求めることが出来る。X線回折パターンより結晶構造を同定し、三斜晶の結晶構造を有する2θ=29.6°付近における(200)面の回折ピーク、及び2θ=22.4°付近における(002)面の回折ピークよりそれぞれ半値幅を求めることができる。   A method for calculating the half width of the positive electrode active material can be obtained by a powder X-ray diffraction method. The crystal structure is identified from the X-ray diffraction pattern, the diffraction peak of (200) plane near 2θ = 29.6 ° having the crystal structure of triclinic crystal, and the diffraction of (002) plane near 2θ = 22.4 °. The full width at half maximum can be obtained from each peak.

正極活物質の平均一次粒子径の算出方法は以下の通りである。まず、正極活物質粒子を走査型電子顕微鏡にて観察し、100個以上の一次粒子を撮像する。得られた画像の粒子一つ一つの面積を算出した後、円相当径に換算して粒子径とし、それらの平均値を一次粒子径とすればよい。   The calculation method of the average primary particle diameter of the positive electrode active material is as follows. First, the positive electrode active material particles are observed with a scanning electron microscope, and 100 or more primary particles are imaged. After calculating the area of each particle of the obtained image, the particle diameter is converted to the equivalent circle diameter, and the average value thereof may be the primary particle diameter.

<正極活物質の製造方法>
正極活物質の製造方法は特に限定されないが、固相合成、水熱合成、カーボサーマルリダクション法などにより合成できることが知られている。以下に、本実施形態に係る水熱合成法を用いた正極活物質の製造方法について説明する。
<Method for producing positive electrode active material>
Although the manufacturing method of a positive electrode active material is not specifically limited, It is known that it can synthesize | combine by a solid-phase synthesis, a hydrothermal synthesis, the carbothermal reduction method etc. Below, the manufacturing method of the positive electrode active material using the hydrothermal synthesis method which concerns on this embodiment is demonstrated.

<水熱合成法>
本実施形態で説明する水熱合成法の製造工程は、原料調製工程、水熱合成工程、乾燥工程及び焼成工程を備える。ただし、乾燥工程を行わずに焼成工程を実施しても良い。焼成工程後に必要に応じて粉砕工程及び分級工程を実施しても良い。
<Hydrothermal synthesis method>
The manufacturing process of the hydrothermal synthesis method described in the present embodiment includes a raw material preparation process, a hydrothermal synthesis process, a drying process, and a firing process. However, you may implement a baking process, without performing a drying process. You may implement a grinding | pulverization process and a classification process as needed after a baking process.

原料調製工程では、リチウム源、バナジウム源、リン源及び水を攪拌、混合して、混合液を調製する。原料調製工程では、リチウム源、バナジウム源、リン源及び水を同時に混合することが好ましい。また、必要に応じて還元剤を加えても良い。   In the raw material preparation step, a lithium source, a vanadium source, a phosphorus source, and water are stirred and mixed to prepare a mixed solution. In the raw material preparation step, it is preferable to mix a lithium source, a vanadium source, a phosphorus source and water at the same time. Moreover, you may add a reducing agent as needed.

リチウム源としては、例えば、LiCO、LiF、LiNO、LiOH、LiCl、LiBr、LiI、LiSO、LiPO及びCHCOOLi及びこれらの水和物からなる群より選ばれる一種又は二種以上を用いることができる。特に、水溶性のリチウム塩を用いた場合、リチウムイオン二次電池の放電容量が向上する傾向がある。水溶性のリチウム塩としては、例えば、LiNO、LiOH、LiCl、LiI、LiSO及びCHCOOLi及びこれらの水和物が挙げられる。 The lithium source is, for example, selected from the group consisting of Li 2 CO 3 , LiF, LiNO 3 , LiOH, LiCl, LiBr, LiI, Li 2 SO 4 , Li 3 PO 4, CH 3 COOLi, and hydrates thereof. One kind or two or more kinds can be used. In particular, when a water-soluble lithium salt is used, the discharge capacity of the lithium ion secondary battery tends to be improved. Examples of the water-soluble lithium salt include LiNO 3 , LiOH, LiCl, LiI, Li 2 SO 4 and CH 3 COOLi, and hydrates thereof.

リン源としては、例えば、HPO、NHPO及び(NHHPOからなる群より選ばれる少なくとも一種を用いることができる。なお、二種以上のリン源を併用してもよい。 As the phosphorus source, for example, at least one selected from the group consisting of H 3 PO 4 , NH 4 H 2 PO 4 and (NH 4 ) 2 HPO 4 can be used. Two or more phosphorus sources may be used in combination.

バナジウム源としては、例えば、金属バナジウム、V、V又はNHVOのいずれかを用いることができる。なお、二種以上のバナジウム源を併用してもよい。 As the vanadium source, for example, any of metal vanadium, V 2 O 3 , V 2 O 5, or NH 4 VO 3 can be used. Two or more vanadium sources may be used in combination.

リチウム源、バナジウム源及びリン源の配合比は、リチウム源に含まれるリチウムのモル数、バナジウム源に含まれるバナジウムのモル数、リン源に含まれるリンのモル数の比が、1:1:1となるように調整すればよい。つまり、混合物中のLi,V及びPのモル比を、LiVOPOの化学量論比(1:1:1)になるように調整すればよい。なお、配合比は、必ずしも上記の化学量論比を満たさなくてもよい。例えば、最終的に得られる活物質におけるLiの欠損を防止するために、リチウム源を多めに配合してもよい。つまり、混合物中のLi,V及びPのモル比を、敢えて上1:1:1からずらしてもよい。 The mixing ratio of the lithium source, the vanadium source and the phosphorus source is such that the ratio of the number of moles of lithium contained in the lithium source, the number of moles of vanadium contained in the vanadium source, and the number of moles of phosphorus contained in the phosphorus source is 1: 1: It may be adjusted to be 1. That is, the molar ratio of Li, V and P in the mixture may be adjusted so as to be the stoichiometric ratio of LiVOPO 4 (1: 1: 1). Note that the blending ratio does not necessarily satisfy the above stoichiometric ratio. For example, in order to prevent the loss of Li in the finally obtained active material, a large amount of lithium source may be blended. That is, the molar ratio of Li, V and P in the mixture may be deliberately shifted from 1: 1: 1.

還元剤としては特に限定されないが、例えば、ヒドラジン(NHNH・HO)又は過酸化水素(H)等を用いることができる。 No particular limitation is imposed on the reducing agent, for example, hydrazine (NH 2 NH 2 · H 2 O) or hydrogen peroxide (H 2 O 2) or the like can be used.

水熱合成工程では、まず、内部を加熱、加圧する機能を有する反応容器(例えば、オートクレーブ等)内に、上述したリチウム源、リン酸源、バナジウム源、水及び還元剤を投入して、これらが分散した水溶液を調製する。続いて、反応容器を密閉して混合物を加圧しながら加熱することにより、混合物中で水熱反応を進行させる。なお、混合物を加圧しながら加熱する時間は、混合物の量に応じて適宜調整すればよい。   In the hydrothermal synthesis step, first, the above-described lithium source, phosphate source, vanadium source, water, and reducing agent are put into a reaction vessel (for example, an autoclave) having a function of heating and pressurizing the inside. An aqueous solution in which is dispersed is prepared. Subsequently, the reaction vessel is sealed and heated while pressurizing the mixture, thereby causing a hydrothermal reaction to proceed in the mixture. In addition, what is necessary is just to adjust suitably the time which heats a mixture, pressurizing according to the quantity of a mixture.

乾燥工程では、80〜300℃程度で加熱すればよい。乾燥方法としては、オーブン乾燥、スプレードライヤー、フラッシュジェットドライヤーなどを用いることができる。   What is necessary is just to heat at about 80-300 degreeC in a drying process. As a drying method, oven drying, spray dryer, flash jet dryer or the like can be used.

焼成工程の加熱処理手法は任意であるが、例えば箱形炉、管状炉、トンネル炉、ロータリーキルン等を使用することができる。加熱処理は、通常、昇温・最高温度保持・降温の三部分に分けられ、更に、昇温・最高温度保持・降温の工程を2回又はそれ以上繰り返し行なってもよい。また、加熱処理と加熱処理との間に、二次粒子を破壊しない程度に凝集を解消することを意味する解砕工程を挟んで行なってもよい。   The heat treatment method of the firing step is arbitrary, and for example, a box furnace, a tubular furnace, a tunnel furnace, a rotary kiln, or the like can be used. The heat treatment is usually divided into three parts of temperature rise, maximum temperature hold, and temperature drop, and the steps of temperature rise, maximum temperature hold, and temperature drop may be repeated twice or more. Further, a crushing step that means eliminating aggregation to such an extent that the secondary particles are not destroyed may be sandwiched between the heat treatments.

焼成工程の雰囲気は特に限定されないが、大気雰囲気であることが好ましい。一方、アルゴン雰囲気中、酸素雰囲気中、窒素雰囲気中またはそれらの混合雰囲気中で行なってもよい。   Although the atmosphere of a baking process is not specifically limited, It is preferable that it is an air atmosphere. On the other hand, you may carry out in argon atmosphere, oxygen atmosphere, nitrogen atmosphere, or those mixed atmosphere.

粉砕工程では、粉砕方法として例えば遊星ボールミル、ジェットミル等を用いることができる。粉砕により、一次粒子または二次粒子が微小化する。なお、粉砕工程は、リチウムイオン二次電池の正極活物質層を作製する時点で実施しても良い。正極活物質層14の作製工程では、活物質、導電助剤、バインダー及び溶媒等から調製したスラリーを正極集電体12上に塗布し、乾燥することにより正極活物質層14が形成される。また粉砕工程では、正極活物質と導電助剤との混合物を粉砕してもよい。また、スラリーそのものに粉砕処理を施してもよい。   In the pulverization step, for example, a planetary ball mill or a jet mill can be used as a pulverization method. By the pulverization, the primary particles or the secondary particles are micronized. In addition, you may implement a grinding | pulverization process at the time of producing the positive electrode active material layer of a lithium ion secondary battery. In the manufacturing process of the positive electrode active material layer 14, a slurry prepared from an active material, a conductive additive, a binder, a solvent, and the like is applied on the positive electrode current collector 12 and dried to form the positive electrode active material layer 14. Moreover, you may grind | pulverize the mixture of a positive electrode active material and a conductive support agent in a grinding | pulverization process. Further, the slurry itself may be pulverized.

分級工程では、焼成工程で得た生成物あるいは粉砕工程で得られた生成物を分級することによって、粗大粒子や微小粒子を除去することができる。分級は、乾燥等が不要で、スケールアップが容易である等の利点を有することから湿式に比べ乾式が好ましい。乾式分級機としては、例えば、振動ふるい機、超音波振動ふるい機、サイクロン、ミクロン、セパレータ、高精度気流分級機等が挙げられる。また、必要に応じて複数回、分級工程を繰り返してもよい。
<正極>
続いて、本実施形態に係る正極10について説明する。
In the classification step, coarse particles and fine particles can be removed by classifying the product obtained in the firing step or the product obtained in the pulverization step. The classification has advantages such as that drying is not necessary and scale-up is easy, and the dry method is preferable to the wet method. Examples of the dry classifier include a vibration sieve machine, an ultrasonic vibration sieve machine, a cyclone, a micron, a separator, and a high-precision airflow classifier. Moreover, you may repeat a classification process in multiple times as needed.
<Positive electrode>
Subsequently, the positive electrode 10 according to the present embodiment will be described.

正極10の正極集電体12としては、例えば、アルミニウム箔等を使用できる。正極活物質層14は、少なくとも上記本実施形態に係る正極活物質と導電助剤とを含有する。正極活物質層14は正極活物質及び導電助剤を結着するバインダーを含んでもよい。   As the positive electrode current collector 12 of the positive electrode 10, for example, an aluminum foil or the like can be used. The positive electrode active material layer 14 contains at least the positive electrode active material according to the present embodiment and a conductive additive. The positive electrode active material layer 14 may include a binder that binds the positive electrode active material and the conductive additive.

導電助剤としては、カーボンブラック類等の炭素材料、銅、ニッケル、ステンレス、鉄等の金属粉、炭素材料及び金属粉の混合物、ITOのような導電性酸化物が挙げられる。   Examples of the conductive aid include carbon materials such as carbon blacks, metal powders such as copper, nickel, stainless steel, and iron, a mixture of carbon materials and metal powders, and conductive oxides such as ITO.

バインダーは、正極活物質と導電助剤とを正極集電体12に結着することができれば特に限定されず、公知の結着剤を使用できる。例えば、ポリフッ化ビニリデン(PVDF)、ポリテトラフルオロエチレン(PTFE)、フッ化ビニリデン―ヘキサフルオロプロピレン共重合体等のフッ素樹脂が挙げられる。   The binder is not particularly limited as long as the positive electrode active material and the conductive additive can be bound to the positive electrode current collector 12, and a known binder can be used. Examples thereof include fluororesins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and vinylidene fluoride-hexafluoropropylene copolymer.

正極活物質層14の正極活物質と導電助剤とバインダーの比率は特に限定されないが、正極活物質の比率が少ないと電極密度が小さくなる傾向にあり、正極活物質の比率は80重量%以上が好ましい。   The ratio of the positive electrode active material, the conductive additive, and the binder of the positive electrode active material layer 14 is not particularly limited, but the electrode density tends to decrease when the ratio of the positive electrode active material is small, and the ratio of the positive electrode active material is 80% by weight or more. Is preferred.

このような正極10は、公知の方法、例えば、正極活物質、導電助剤及びバインダーを、それらの種類に応じた溶媒、例えばPVDFの場合はN−メチル−2−ピロリドン、N,N−ジメチルホルムアミド等の溶媒に添加したスラリーを、正極集電体12の表面に塗布し、乾燥させることにより製造できる。   Such a positive electrode 10 is prepared by a known method, for example, a positive electrode active material, a conductive additive and a binder, and a solvent corresponding to the type thereof, for example, N-methyl-2-pyrrolidone, N, N-dimethyl in the case of PVDF. The slurry can be produced by applying a slurry added to a solvent such as formamide on the surface of the positive electrode current collector 12 and drying it.

<負極>
負極集電体22としては、銅箔等を使用できる。また、負極活物質層24としては、負極活物質、導電助剤、及び、バインダーを含むものを使用できる。導電助剤としては特に限定されず、炭素材料、金属粉などが使用できる。負極に用いられるバインダーとしては、ポリフッ化ビニリデン(PVDF)、ポリテトラフルオロエチレン(PTFE)、テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体(FEP)等のフッ素樹脂が使用できる。
<Negative electrode>
As the negative electrode current collector 22, a copper foil or the like can be used. Moreover, as the negative electrode active material layer 24, the thing containing a negative electrode active material, a conductive support agent, and a binder can be used. It does not specifically limit as a conductive support agent, A carbon material, a metal powder, etc. can be used. As the binder used for the negative electrode, fluororesins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) can be used.

負極活物質としては、黒鉛、難黒鉛化炭素等の炭素材料、Al、Si、Sn等のリチウムと化合することのできる金属、SiO、SnO等の酸化物を主体とする非晶質の化合物、チタン酸リチウム(LiTi12)等を含む粒子が挙げられる。 As the negative electrode active material, carbon materials such as graphite and non-graphitizable carbon, metals that can be combined with lithium such as Al, Si and Sn, and amorphous materials mainly composed of oxides such as SiO 2 and SnO 2 Examples thereof include particles containing a compound, lithium titanate (Li 4 Ti 5 O 12 ), and the like.

負極20の製造方法は、正極10の製造方法と同様にスラリーを調整して負極集電体22に塗布すればよい。   The negative electrode 20 may be manufactured by adjusting the slurry and applying it to the negative electrode current collector 22 in the same manner as the positive electrode 10.

<電解液>
電解液としては、特に限定されず、例えば、本実施形態では、有機溶媒にリチウム塩を含む電解液を使用することができる。リチウム塩としては、例えば、LiPF、LiClO、LiBF等の塩が使用できる。なお、これらの塩は1種を単独で使用してもよく、2種以上を併用してもよい。
<Electrolyte>
The electrolytic solution is not particularly limited. For example, in the present embodiment, an electrolytic solution containing a lithium salt in an organic solvent can be used. Examples of the lithium salt, LiPF 6, LiClO 4, salts of LiBF 4 or the like can be used. In addition, these salts may be used individually by 1 type, and may use 2 or more types together.

有機溶媒としては、例えば、プロピレンカーボネート、エチレンカーボネート、及び、ジエチルカーボネート、ジメチルカーボネート、メチルエチルカーボネート等が好ましく挙げられる。これらは単独で使用してもよく、2種以上を任意の割合で混合して使用してもよい。   Preferable examples of the organic solvent include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate. These may be used alone or in combination of two or more at any ratio.

また、セパレータ18は、ポリエチレン、ポリプロピレン又はポリオレフィンからなるフィルムの単層体、積層体や上記樹脂の混合物の延伸膜、或いは、セルロース、ポリエステル及びポリプロピレンからなる群より選択される少なくとも1種の構成材料からなる繊維不織布が使用できる。   The separator 18 is a monolayer of a film made of polyethylene, polypropylene or polyolefin, a stretched film of a laminate or a mixture of the above resins, or at least one constituent material selected from the group consisting of cellulose, polyester and polypropylene. The fiber nonwoven fabric which consists of can be used.

ケース50は、その内部に積層体30及び電解液を密封するものである。ケース50は、電解液の外部への漏出や、外部からのリチウムイオン二次電池100内部への水分等の侵入等を抑止できる物であれば特に限定されず、例えば、金属ラミネートフィルムを利用できる。   The case 50 seals the laminated body 30 and the electrolytic solution therein. The case 50 is not particularly limited as long as it can prevent leakage of the electrolytic solution to the outside and entry of moisture and the like into the lithium ion secondary battery 100 from the outside. For example, a metal laminate film can be used. .

リード60,62は、アルミ等の導電材料から形成されている。   The leads 60 and 62 are made of a conductive material such as aluminum.

本正極活物質は、リチウムイオン二次電池以外の電気化学素子の電極材料としても用いることができる。このような、電気化学素子としては、金属リチウム二次電池(正極に本発明の正極活物質粒子を含む電極を用い、負極に金属リチウムを用いたもの)等のリチウムイオン二次電池以外の二次電池や、リチウムキャパシタ等の電気化学キャパシタ等が挙げられる。   This positive electrode active material can also be used as an electrode material for electrochemical elements other than lithium ion secondary batteries. As such an electrochemical element, a lithium ion secondary battery other than a lithium ion secondary battery such as a metal lithium secondary battery (an electrode including the positive electrode active material particles of the present invention as a positive electrode and metal lithium as a negative electrode) is used. Examples thereof include secondary batteries and electrochemical capacitors such as lithium capacitors.

以下、実施例及び比較例に基づいて本発明をより具体的に説明するが、本発明は以下の実施例に限定されるものではない。   EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

(実施例1)
[正極活物質の作製]
とLiOH・HOとHPOをモル比およそ1:2:2となるように秤量し、蒸留水中に投入し、これらをマグネチックスターラーにて1時間攪拌した。激しく攪拌しながらヒドラジン1水和物(NHNH・HO)を少量ずつ滴下し、さらに1時間攪拌して原料を調製した。その後、オートクレーブ用ガラス容器に混合液を移し替えた。容器を密閉し、攪拌しながら160℃で8時間加熱し、水熱合成を行った。得られたペーストを100℃のオーブンにて12時間乾燥した。得られた乾燥粉末を乳鉢により解砕した後、箱型炉にて大気中650℃、4時間焼成した。
Example 1
[Preparation of positive electrode active material]
V 2 O 5 , LiOH.H 2 O and H 3 PO 4 were weighed so as to have a molar ratio of about 1: 2: 2, poured into distilled water, and stirred with a magnetic stirrer for 1 hour. Hydrazine monohydrate (NH 2 NH 2 .H 2 O) was added dropwise little by little with vigorous stirring, and the mixture was further stirred for 1 hour to prepare a raw material. Thereafter, the mixed solution was transferred to a glass container for autoclave. The vessel was sealed and heated at 160 ° C. for 8 hours with stirring to perform hydrothermal synthesis. The obtained paste was dried in an oven at 100 ° C. for 12 hours. The obtained dry powder was pulverized with a mortar and then baked in the box furnace at 650 ° C. for 4 hours in the air.

得られた正極活物質について、誘導結合プラズマ法(以下、ICP法)による組成分析を行った結果、組成はLiVOPOであることが確認された。 The obtained positive electrode active material was subjected to composition analysis by an inductively coupled plasma method (hereinafter, ICP method), and as a result, it was confirmed that the composition was LiVOPO 4 .

得られた正極活物質と、導電助剤であるアセチレンブラックと、ケッチェンブラックとを、80:5:5の重量比で秤量し、容器に入れ、遊星型ボールミルによる粉砕処理を回転数550rpmにて10分間行った。   The obtained positive electrode active material, acetylene black as a conductive auxiliary agent, and ketjen black are weighed at a weight ratio of 80: 5: 5, put in a container, and pulverized by a planetary ball mill at a rotational speed of 550 rpm. For 10 minutes.

得られた正極活物質と導電助剤との混合物について、粉末X線回折法により結晶構造の同定と半値幅を求めた。X線回折装置として株式会社リガク社製「UltimaIV」を用い、以下の測定条件にて行った。
[測定条件]
Filter: Ni
ターゲット:Cu Kα 1.54060Å
X線出力設定:40kV−40mA
スリット:発散1/2°、散乱1/2°、受光0.15mm
走査速度:2°/min
サンプリング幅:0.02°
結晶構造は三斜晶LiVOPOであることを確認し、2θ=29.6°付近における(200)面の回折ピークの半値幅は0.164°であり、さらに、2θ=22.4°付近における(002)面の回折ピークの半値幅は0.173°であった。
About the mixture of the obtained positive electrode active material and conductive support agent, the identification and the half value width of the crystal structure were calculated | required by the powder X ray diffraction method. Using “UltimaIV” manufactured by Rigaku Corporation as an X-ray diffractometer, the measurement was performed under the following measurement conditions.
[Measurement condition]
Filter: Ni
Target: Cu Kα 1.54060Å
X-ray output setting: 40kV-40mA
Slit: Divergence 1/2 °, scattering 1/2 °, light receiving 0.15mm
Scanning speed: 2 ° / min
Sampling width: 0.02 °
The crystal structure was confirmed to be triclinic LiVOPO 4 , and the half value width of the diffraction peak of the (200) plane at around 2θ = 29.6 ° was 0.164 °, and further, around 2θ = 22.4 °. The half-value width of the diffraction peak on the (002) plane was 0.173 °.

粉砕処理を行った正極活物質粒子を走査型電子顕微鏡にて観察し、前述の方法で平均一次粒子径を求めたところ、0.31μmであった。   The positive electrode active material particles subjected to the pulverization treatment were observed with a scanning electron microscope, and the average primary particle diameter was determined by the above-described method, which was 0.31 μm.

[評価用セルの作製]
実施例1の正極活物質と導電助剤との混合物とバインダーであるポリフッ化ビニリデン(PVDF、呉羽化学製KF7305)とを重量比を90:10で混合したものを、溶媒であるN−メチル−2−ピロリドン(NMP)中に分散させてスラリーを調製した。このスラリーを集電体であるアルミニウム箔上に塗布し、乾燥させた後、圧延を行い、正極活物質層が形成された正極を作製した。
[Production of evaluation cell]
A mixture of the positive electrode active material and conductive additive of Example 1 and polyvinylidene fluoride (PVDF, Kureha Chemical KF7305) as a binder in a weight ratio of 90:10 was mixed with N-methyl- A slurry was prepared by dispersing in 2-pyrrolidone (NMP). This slurry was applied onto an aluminum foil as a current collector, dried, and then rolled to produce a positive electrode on which a positive electrode active material layer was formed.

次に、負極として人造黒鉛(BTR社製FSN)とポリフッ化ビニリデン(PVdF)のNメチルピロリドン(NMP)5wt%溶液を人造黒鉛:ポリフッ化ビニリデン=93:7の割合になるように混合し、スラリー状の塗料を作製した。塗料を集電体である銅箔に塗布し、乾燥、圧延することによって負極を作製した。   Next, artificial graphite (FSN manufactured by BTR) and N methylpyrrolidone (NMP) 5 wt% solution of polyvinylidene fluoride (PVdF) as a negative electrode were mixed so that the ratio of artificial graphite: polyvinylidene fluoride = 93: 7 was obtained. A slurry paint was prepared. The negative electrode was produced by apply | coating a coating material to the copper foil which is a collector, and drying and rolling.

正極と、負極とを、それらの間にポリエチレン微多孔膜からなるセパレータを挟んで積層し、積層体(素体)を得た。この積層体を、アルミラミネートパックに入れた。電解液はエチレンカーボネート(EC)、ジエチルカーボネート(DEC)を体積比3:7で混合し、支持塩としてLiPFを1mol/Lになるよう溶解した。 A positive electrode and a negative electrode were laminated with a separator made of a polyethylene microporous film interposed therebetween to obtain a laminate (element body). This laminate was placed in an aluminum laminate pack. As the electrolytic solution, ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 3: 7, and LiPF 6 was dissolved as a supporting salt to a concentration of 1 mol / L.

積層体を入れたアルミラミネートパックに、上記電解液を注入した後、真空シールし、実施例1の評価用セルを作製した。   The above electrolyte was poured into an aluminum laminate pack containing the laminate, and then vacuum-sealed to produce an evaluation cell of Example 1.

[電池特性の測定]
実施例1の評価用セルを、25℃で、電流値18mA/gで4.3Vまで定電流で充電した後、電流値18mA/gで2.8Vまで定電流放電した。このとき、実施例1の放電容量は131mAh/gであった(初期放電容量)。この充放電サイクルを100サイクル繰返すサイクル試験を行った。実施例1の評価用セルの初期放電容量を100%とすると、100サイクル後の放電容量は92.8%であった。以下では、初期放電容量を100%としたときの、100サイクル後の放電容量の割合を容量維持率という。容量維持率が高いことは、電池が充放電サイクル耐久性に優れていることを示す。
[Measurement of battery characteristics]
The evaluation cell of Example 1 was charged at a constant current of up to 4.3 V at 25 ° C. with a current value of 18 mA / g and then discharged at a constant current of 2.8 V at a current value of 18 mA / g. At this time, the discharge capacity of Example 1 was 131 mAh / g (initial discharge capacity). A cycle test was repeated for 100 cycles of this charge / discharge cycle. When the initial discharge capacity of the evaluation cell of Example 1 was 100%, the discharge capacity after 100 cycles was 92.8%. Hereinafter, the ratio of the discharge capacity after 100 cycles when the initial discharge capacity is 100% is referred to as a capacity maintenance rate. A high capacity retention rate indicates that the battery is excellent in charge / discharge cycle durability.

(実施例2)
遊星型ボールミルによる粉砕処理の回転数を520rpmとした以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Example 2)
A positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared in the same manner as in Example 1 except that the rotational speed of the pulverization treatment by the planetary ball mill was 520 rpm, and the (200) plane and (002) ) The half width of the diffraction peak of the surface and the average primary particle diameter were determined, and the evaluation cell was produced and the battery characteristics were evaluated. The results are shown in Table 1.

(実施例3)
遊星型ボールミルによる粉砕処理の回転数を480rpm、粉砕時間を20分間とし、粉砕工程後に目開き20μmのふるいを用いた10分間の振動ふるい処理によりふるい上に残った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Example 3)
Except that the rotation speed of the grinding process by the planetary ball mill is 480 rpm, the grinding time is 20 minutes, and the powder remaining on the sieve is used after the grinding process by the vibration sieve process for 10 minutes using the sieve having an opening of 20 μm. In the same manner as in Example 1, a positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared, and the half-value width and average primary particle diameter of diffraction peaks on the (200) plane and (002) plane were determined and evaluated. Cell production and battery characteristic evaluation were performed. The results are shown in Table 1.

(実施例4)
乾燥粉末の焼成温度を640℃とし、遊星型ボールミルによる粉砕時間を20分間とし、粉砕工程後に目開き20μmのふるいを用いた振動ふるい処理によりふるいを通った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
Example 4
Example 1 except that the firing temperature of the dry powder was 640 ° C., the pulverization time with a planetary ball mill was 20 minutes, and the powder that passed through the sieve was vibrated using a sieve with an opening of 20 μm after the pulverization step. A positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared in the same manner as described above, and the half-value width and average primary particle size of diffraction peaks of the (200) plane and (002) plane were determined, and the evaluation cell And battery characteristics were evaluated. The results are shown in Table 1.

(実施例5)
乾燥粉末の焼成温度を640℃とし、遊星型ボールミルによる粉砕時間を30分間とし、粉砕工程後に目開き20μmのふるいを用いた振動ふるい処理によりふるいを通った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Example 5)
Example 1 except that the firing temperature of the dry powder was 640 ° C., the pulverization time with a planetary ball mill was 30 minutes, and the powder that passed through the sieve was vibrated using a sieve having an opening of 20 μm after the pulverization step. A positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared in the same manner as described above, and the half-value width and average primary particle size of diffraction peaks of the (200) plane and (002) plane were determined, and the evaluation cell And battery characteristics were evaluated. The results are shown in Table 1.

(実施例6)
粉砕工程後に目開き53μmのふるいを用いた振動ふるい処理によりふるいを通った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Example 6)
A positive electrode active material and a mixture of a positive electrode active material and a conductive additive were prepared in the same manner as in Example 1 except that powder that passed through a sieve by vibration sieving using a sieve having an aperture of 53 μm was used after the pulverization step. Then, the half-value width and average primary particle diameter of diffraction peaks of the (200) plane and the (002) plane were determined, and an evaluation cell was prepared and battery characteristics were evaluated. The results are shown in Table 1.

(実施例7)
粉砕工程後に目開き20μmのふるいを用いた10分間の振動ふるい処理によりふるい上に残った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Example 7)
The positive electrode active material, the positive electrode active material, and the conductive auxiliary agent were used in the same manner as in Example 1 except that the powder remaining on the sieve was vibrated for 10 minutes using a sieve having an opening of 20 μm after the pulverization step. A half-width and an average primary particle diameter of diffraction peaks on the (200) plane and the (002) plane were obtained, and evaluation cells were prepared and battery characteristics were evaluated. The results are shown in Table 1.

(実施例8)
乾燥粉末の焼成温度を660℃とし、粉砕工程後に目開き20μmのふるいを用いた10分間の振動ふるい処理によりふるい上に残った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Example 8)
In the same manner as in Example 1, except that the firing temperature of the dry powder was set to 660 ° C. and the powder remaining on the sieve was subjected to vibration sieving for 10 minutes using a sieve having an opening of 20 μm after the pulverization step. A mixture of the active material, the positive electrode active material, and the conductive additive is prepared, and the half-value width and average primary particle diameter of the diffraction peaks of the (200) plane and the (002) plane are obtained, and the evaluation cell is manufactured and the battery characteristics are evaluated. went. The results are shown in Table 1.

(実施例9)
粉砕工程後に目開き45μmのふるいを用いた振動ふるい処理によりふるいを通おり、かつ目開き20μmのふるいを用いた10分間の振動ふるい処理によりふるい上に残った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
Example 9
Example, except that after the pulverization step, the sieve was passed by a vibration sieve treatment using a sieve with an opening of 45 μm, and the powder remaining on the sieve by a vibration sieve treatment for 10 minutes using a sieve with an opening of 20 μm was used. In the same manner as in No. 1, a positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared, and the half-value width and average primary particle size of the diffraction peaks on the (200) plane and (002) plane were determined for evaluation. Cell preparation and battery characteristic evaluation were performed. The results are shown in Table 1.

(実施例10)
乾燥粉末の焼成温度を640℃とし、遊星型ボールミルによる粉砕時間を30分間とし、粉砕工程後に目開き53μmのふるいを用いた振動ふるい処理によりふるいを通った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Example 10)
Example 1 except that the firing temperature of the dry powder was 640 ° C., the pulverization time with a planetary ball mill was 30 minutes, and the powder that passed through the sieve was vibrated using a sieve having an aperture of 53 μm after the pulverization step. A positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared in the same manner as described above, and the half-value width and average primary particle size of diffraction peaks of the (200) plane and (002) plane were determined, and the evaluation cell And battery characteristics were evaluated. The results are shown in Table 1.

(比較例1)
遊星型ボールミルによる粉砕処理の回転数を600rpmとした以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Comparative Example 1)
A positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared in the same manner as in Example 1 except that the rotational speed of the pulverization treatment by the planetary ball mill was 600 rpm, and the (200) plane and (002) ) The half width of the diffraction peak of the surface and the average primary particle diameter were determined, and the evaluation cell was produced and the battery characteristics were evaluated. The results are shown in Table 1.

(比較例2)
乾燥粉末の焼成温度を640℃とし、遊星型ボールミルによる粉砕処理の回転数を570rpm、粉砕時間を20分間とし、粉砕工程後に目開き20μmのふるいを用いた振動ふるい処理によりふるいを通った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Comparative Example 2)
The dried powder was fired at a temperature of 640 ° C., the rotational speed of the pulverization process by the planetary ball mill was 570 rpm, the pulverization time was 20 minutes, and the powder passed through the sieve by the vibration sieve process using a sieve with an opening of 20 μm after the pulverization process. A positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared in the same manner as in Example 1 except that they were used, and the half-value width and average primary of diffraction peaks on the (200) plane and the (002) plane were prepared. The particle diameter was determined, and an evaluation cell was prepared and battery characteristics were evaluated. The results are shown in Table 1.

(比較例3)
乾燥粉末の焼成温度を640℃とし、遊星型ボールミルによる粉砕処理の回転数を600rpmとし、粉砕工程後に目開き20μmのふるいを用いた振動ふるい処理によりふるいを通った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Comparative Example 3)
The dry powder was fired at a temperature of 640 ° C., the rotational speed of the grinding process with a planetary ball mill was 600 rpm, and the powder passed through the sieve by vibration sieve treatment using a sieve with an opening of 20 μm was used after the grinding process. In the same manner as in Example 1, a positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared, and the half-value width and average primary particle diameter of diffraction peaks on the (200) plane and (002) plane were determined and evaluated. Cell production and battery characteristic evaluation were performed. The results are shown in Table 1.

(比較例4)
乾燥粉末の焼成温度を640℃とし、遊星型ボールミルによる粉砕処理の回転数を600rpmとし、粉砕工程後に目開き45μmのふるいを用いた振動ふるい処理によりふるいを通った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Comparative Example 4)
Implemented except that the firing temperature of the dry powder was 640 ° C., the rotational speed of the grinding process with a planetary ball mill was 600 rpm, and the powder that passed through the sieve was vibrated using a sieve with an opening of 45 μm after the grinding process. In the same manner as in Example 1, a positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared, and the half-value width and average primary particle diameter of diffraction peaks on the (200) plane and (002) plane were determined and evaluated. Cell production and battery characteristic evaluation were performed. The results are shown in Table 1.

(比較例5)
乾燥粉末の焼成温度を640℃とし、遊星型ボールミルによる粉砕処理の回転数を600rpmとし、粉砕工程後に目開き53μmのふるいを用いた振動ふるい処理によりふるいを通った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Comparative Example 5)
Implemented except that the firing temperature of the dry powder was 640 ° C., the rotational speed of the grinding process by the planetary ball mill was 600 rpm, and the powder that passed through the sieve was vibrated using a sieve with an opening of 53 μm after the grinding process. In the same manner as in Example 1, a positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared, and the half-value width and average primary particle diameter of diffraction peaks on the (200) plane and (002) plane were determined and evaluated. Cell production and battery characteristic evaluation were performed. The results are shown in Table 1.

(比較例6)
乾燥粉末の焼成温度を660℃とし、遊星型ボールミルによる粉砕処理の回転数を480rpmとし、粉砕工程後に目開き20μmのふるいを用いた10分間の振動ふるい処理によりふるい上に残った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Comparative Example 6)
The dry powder firing temperature was set to 660 ° C., the rotation speed of the grinding process by the planetary ball mill was set to 480 rpm, and the powder remaining on the sieve was used after the grinding process by a vibration sieve process for 10 minutes using a sieve having an opening of 20 μm. Except for the above, a positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared in the same manner as in Example 1, and the half width of the diffraction peaks on the (200) plane and (002) plane and the average primary particle diameter The cell for evaluation and battery characteristic evaluation were performed. The results are shown in Table 1.

(比較例7)
乾燥粉末の焼成温度を660℃とし、遊星型ボールミルによる粉砕処理を行わず、目開き20μmのふるいを用いた10分間の振動ふるい処理によりふるい上に残った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Comparative Example 7)
Example 1 except that the firing temperature of the dry powder was set to 660 ° C., the powder remaining on the sieve was used by vibration sieving for 10 minutes using a sieve having a mesh size of 20 μm, without performing a pulverization treatment with a planetary ball mill. A positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared in the same manner as described above, and the half-value width and average primary particle size of diffraction peaks of the (200) plane and (002) plane were determined, and the evaluation cell And battery characteristics were evaluated. The results are shown in Table 1.

(比較例8)
乾燥粉末の焼成温度を660℃とし、遊星型ボールミルによる粉砕処理を行わず、目開き53μmのふるいを用いた振動ふるい処理によりふるいを通おり、かつ目開き20μmのふるいを用いた10分間の振動ふるい処理によりふるい上に残った粉末を用いた以外は、実施例1と同様の方法で、正極活物質及び正極活物質と導電助剤との混合物を作製し、(200)面および(002)面の回折ピークの半値幅、平均一次粒子径を求め、評価用セルの作製、電池特性評価を行った。結果を表1に示す。
(Comparative Example 8)
The firing temperature of the dry powder is 660 ° C., the pulverization process is not performed with a planetary ball mill, the sieve is passed through a vibration sieve process using a sieve with an opening of 53 μm, and the vibration is performed for 10 minutes using a sieve with an opening of 20 μm. A positive electrode active material and a mixture of the positive electrode active material and a conductive additive were prepared in the same manner as in Example 1 except that the powder remaining on the sieve by the sieving treatment was used, and the (200) plane and (002) The full width at half maximum of the diffraction peak of the surface and the average primary particle diameter were determined, and an evaluation cell was prepared and battery characteristics were evaluated. The results are shown in Table 1.

Figure 0006197610
Figure 0006197610

表1から明らかなように、実施例1〜10の正極活物質の(200)面の回折ピークの半値幅は0.114°以上0.174°以下であり、平均一次粒子径は0.07μm以上0.60μm以下であることが確認された。また、実施例1〜10の評価用セルの初期放電容量は128mAh/g以上であり、かつサイクル特性は90.1%以上であることが確認された。さらに、実施例1〜4および6〜9の正極活物質の(002)面の回折ピークの半値幅は0.185°以下であり、サイクル特性は92.1%以上であることが確認された。また、比較例1〜5の評価用セルの初期放電容量は123mAh/g以上であるが、サイクル特性は85%以下であることが確認された。比較例6〜8の評価用セルのサイクル特性は93%以上であるが、初期放電容量は107mAh/g以下であることが確認された。   As is clear from Table 1, the half width of the diffraction peak of the (200) plane of the positive electrode active materials of Examples 1 to 10 is 0.114 ° to 0.174 °, and the average primary particle size is 0.07 μm. It was confirmed that the thickness was 0.60 μm or less. Moreover, it was confirmed that the initial discharge capacity of the evaluation cells of Examples 1 to 10 is 128 mAh / g or more and the cycle characteristics are 90.1% or more. Furthermore, it was confirmed that the half value width of the diffraction peak of the (002) plane of the positive electrode active materials of Examples 1 to 4 and 6 to 9 was 0.185 ° or less, and the cycle characteristics were 92.1% or more. . Moreover, although the initial discharge capacity of the cells for evaluation of Comparative Examples 1 to 5 was 123 mAh / g or more, it was confirmed that the cycle characteristics were 85% or less. The cycle characteristics of the evaluation cells of Comparative Examples 6 to 8 were 93% or more, but the initial discharge capacity was confirmed to be 107 mAh / g or less.

10…正極、20…負極、12…正極集電体、14…正極活物質層、18…セパレータ、22…負極集電体、24…負極活物質層、30…積層体、50…ケース、60,62…リード、100…リチウムイオン二次電池。 DESCRIPTION OF SYMBOLS 10 ... Positive electrode, 20 ... Negative electrode, 12 ... Positive electrode collector, 14 ... Positive electrode active material layer, 18 ... Separator, 22 ... Negative electrode collector, 24 ... Negative electrode active material layer, 30 ... Laminate, 50 ... Case, 60 62 ... Lead, 100 ... Lithium ion secondary battery.

Claims (4)

三斜晶の結晶構造を有するLiVOPOの(200)面の回折ピークの半値幅が0.114°以上0.17°以下であり、かつ、平均一次粒子径が0.07μm以上0.6μm以下であることを特徴とする正極活物質。 Half-width of the diffraction peak of the (200) plane of the LiVOPO 4 having a crystal structure of triclinic is at 0.17 4 ° below 0.114 ° or more and an average primary particle diameter of more than 0.07 .mu.m 0.6 .mu.m A positive electrode active material characterized by: 前記三斜晶の結晶構造を有するLiVOPOの(002)面の回折ピークの半値幅が0.118°以上0.185°以下であることを特徴とする請求項1記載の正極活物質。 2. The positive electrode active material according to claim 1, wherein the half width of the diffraction peak of the (002) plane of LiVOPO 4 having the triclinic crystal structure is 0.118 ° or more and 0.185 ° or less. 集電体と、請求項1又は2記載の正極活物質を含み前記集電体上に設けられた正極活物質層と、を備える正極。   A positive electrode comprising a current collector and a positive electrode active material layer comprising the positive electrode active material according to claim 1 or 2 and provided on the current collector. 請求項3記載の正極を備えるリチウムイオン二次電池。   A lithium ion secondary battery comprising the positive electrode according to claim 3.
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JP5347604B2 (en) * 2009-03-16 2013-11-20 Tdk株式会社 Active material particles mainly composed of α-type crystal structure LiVOPO4, electrode including the same, lithium secondary battery including the electrode, and method for producing the active material particles

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